What Is HIIT and Is It For You?

Benefits of High Intensity Interval Training

Physical Therapy with HIIT

High-Intensity Interval Training (HIIT) – sounds intense doesn’t it? I used to be skeptical of HIIT and whether the claims of its benefits were actually true. Could someone really achieve the same aerobic gains in half the time? Was it safe? Was it only for top-level athletes in a sports science lab? I was skeptical – that is, until I scoured the literature. What I know now, I can share with you and, hopefully, better guide you toward your health and fitness goals.

Let’s look at what HIIT is, its benefits, and how it compares to other types of exercise. We’ll also look at some sample workout regimens and see if HIIT is right for you…

What Is HIIT?

HIIT is a form of interval training where you alternate intense bursts of exercise with less intense exercise. These cycles are repeated until you become too exhausted to continue.

A typical HIIT workout on a stationary bike might look something like this:

  • Warm up at low intensity (50%)
  • High intensity (90-95%) alternating with low intensity (50%) bursts
  • Cool down at low intensity (50%)

If you perform HIIT at near maximal intensity, it would be very difficult to push longer than 20-30 minutes for a workout – trust me.

What Are the Benefits of HIIT?

One obvious benefit of HIIT is that is provides a great workout in a short amount of time.

If you’re like me, you’re busy. Working out is a priority, but I have to squeeze it in where I can – oftentimes I only have 30 minutes.

Perhaps the most sought after benefits of HIIT are an improved athletic capacity1 with significant improvements in cardiovascular fitness2.

HIIT has also been shown to improve glucose metabolism and can even lower insulin resistance3.

To state the obvious, HIIT can also lead to weight loss.

All of these benefits are great, but doesn’t regular exercise provide the same benefits? Yes, but let’s look at how they compare…

How Does HIIT Compare to Continuous Training?

When comparing High-Intensity Interval Training with traditional, moderate-intensity continuous exercise, both lead to significant improvements in cardiovascular fitness. However, greater improvements in VO2max are seen with HIIT4.

VO2 max is your maximal oxygen consumption – it reflects your aerobic physical fitness and endurance capacity.

Just how much better can your physical fitness improve with HIIT?

A 2014 study measuring VO2 max was conducted in individuals with chronic cardiovascular or metabolic diseases (high blood pressure, obesity, heart failure, coronary artery disease, or metabolic syndrome). These participants completed a HIIT exercise program and were compared with another group who completed a moderate-intensity continuous exercise program.

The result? The HIIT group’s VO2 max was nearly double that of the continuous exercise group’s5.

In a nutshell then, if you want to improve your aerobic physical fitness, HIIT is best.”

What else can we compare?

How about Blood vessel function? HIIT is more effective than continuous training at improving blood vessel function and blood vessel health6.

Glucose metabolism? HIIT improves glucose metabolism even more so than in people who participate in continuous exercise7.

What about weight loss? Here’s an area where continuous exercise has HIIT beat. HIIT isn’t as effective as traditional exercise for treating obesity, or improving muscle and bone mass8.

Is HIIT Safe?

The thing about HIIT is – it’s extremely vigorous exercise. It’s near maximal effort, repeatedly, for as long as you can tolerate. Most people aren’t used to this – we usually exercise somewhere in the 60-85% effort zone during continuous exercise. To truly go all-out, over and over again is grueling.

The question then arises: would the general population safely or practically be able to tolerate the extreme nature of the exercise regimen9?

There have been many studies in recent years involving the safety of HIIT in people with heart disease, diabetes, and stroke. Here’s a brief overview:

  • Heart Disease: A recent study looked at 5,000 patients over 7 years of exercise in a supervised cardiac rehabilitation setting. Reports showed a very low risk of acute cardiovascular events with HIIT, with an event rate of 1 non-fatal heart attack per 23,182 hours of HIIT10.
  • Diabetes: It’s currently advised that people with type 2 Diabetes should have a pre-exercise screening, an EKG stress test, and physician clearance before engaging in HIIT, as they would with any vigorous exercise program11.
  • Stroke: Preliminary research has been done on people with stroke to determine the safety of HIIT. The data indicates that people with chronic stroke who are pre-screened with an EKG stress test, a graded exercise test to determine the peak heart rate, and include a harness for fall prevention, are safe to participate in HIIT12.

Based on all the literature I looked at, HIIT doesn’t differ from regular vigorous exercise in terms of safety. Therefore, for people who have been cleared to participate in vigorous exercise, HIIT has shown to have many added health benefits, as we’ve seen.

Sample HIIT Workouts

There isn’t one formula for High-Intensity Interval Training. That said, there are some popular HIIT protocols that have proven to have effective results. Here are a few of them:

  • 2:1 Ratio of work to recovery periods:
    • 30-40 seconds of sprinting
    • Followed by 15-20 seconds of jogging or walking
    • Repeated continuously to fatigue
  • Tabata Regimen:
    • 20 seconds of ultra-intense exercise
    • Followed by 10 seconds of rest
    • Repeated continuously for 4 minutes
    • In the original 1996 Tabata study, Olympic speed-skaters used this method on a cycle ergometer to train 4 times per week plus another day of continuous training. Their gains were similar to another group who trained continuously 5 times per week13
  • Gibala Regimen:
    • 3 minute warm-up
    • 60 seconds of intense exercise
    • Followed by 75 seconds of rest
    • Repeated 8-12 cycles
    • In a 2010 study, people who used this method 3 times per week had gains similar to those who train with continuous exercise 5 times per week14
  • Zuniga Regimen:
    • Intervals of 30 seconds at 90% max power
    • Followed by 30 seconds of rest
    • A 2011 study found this combination to allow for the highest VO2 consumption and the longest workout duration at a specified intensity15
  • Timmons Regimen: On an exercise bike:
    • Warm up
    • Perform 2 minutes of gentle pedaling
    • Followed by 20 seconds of pedaling at max effort
    • Do this for 3 sets
    • Cool-down
    • Complete this cycle 3 times per week for a total of 21 minutes of exercise per week (3 minutes of intense exercise)
  • HIIT for Sedentary Adults: this is a less intense version of the Zuniga regimen. It is intended for people who are sedentary and have done no exercise for more than one year16.
    • 3 minute warm-up
    • 10 reps of 60 second bursts at 80-95% of heart rate reserve
      • Heart rate reserve = max heart rate minus resting heart rate
      • To roughly calculate your max heart rate, take 220 minus your age.
    • Each burst is followed by 60 seconds of recovery
    • 5 minute cool-down

Is HIIT Right For You?

If your primary goal is to lose weight, to build muscle or to improve bone mass, there may be better ways than HIIT.

If, however, you don’t have a lot of time to work out, you’ve been cleared by a physician or you’re in otherwise good health, and if you want to improve your…

  • Aerobic physical fitness
  • Blood vessel health and function
  • Glucose metabolism and Lower insulin resistance

…HIIT might be right for you.

The caveat is that it’s incredibly hard work. It’s not the type of workout you can chat with a friend or read your Kindle during – it will take everything you’ve got.

Are you up for the challenge?

Question: Have you tried HIIT? What are your thoughts? You can leave a comment by clicking here.

  1. Laursen PB, Jenkins DG (2002). The Scientific Basis for High-Intensity Interval Training. Sports Medicine (Review). 32(1):53-73. ↩︎
  2. Milanovic X, et al. (2015) Effectiveness of high-intensity interval training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials. Sports Med. 45(10): 1469-81. ↩︎
  3. Jelleyman C, et al. (2015). The effects of high-intensity interval training on glucose regulation and insulin resistance: a meta-analysis. Obes Rev. 16(11): 942-61. ↩︎
  4. Milanovic X, et al. (2015) Effectiveness of high-intensity interval training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials. Sports Med. 45(10): 1469-81. ↩︎
  5. Weson KS, et al. (2014). High-intensity interval training in patients with lifestyle-induced cardiometabolic disease: a systematic review and meta-analysis. Br J Sports Med. 48(16): 1227-1234. ↩︎
  6. Ramos JS, et al. (2015). The impact of high-intensity interval training versus moderate-intensity continuous training on vascular function: a systematic review and meta-analysis. Sports Med 45(5)679-92. ↩︎
  7. Jelleyman C, et al. (2015). The effects of high-intensity interval training on glucose regulation and insulin resistance: a meta-analysis. Obes Rev. 16(11): 942-61. ↩︎
  8. Nybo, Lars, et al. (2010). High-intensity training versus traditional exercise interventions for promoting health. Medicine and Science in Sports and Exercise. 42 (10): 1951-1958. ↩︎
  9. Gibala MJ (2007). High-intensity interval training: A time-efficient strategy for health promotion? Current Sports Med Rep. 6 (4):211-13. ↩︎
  10. Rognmo O, Modholdt T, Bakken H, et al. Cardiovascular risk of high- versus moderate-intensity aerobic exercise in coronary heart disease pateints. Circulation 2012; 126:1436-1440. ↩︎
  11. Francois ME, Little JP. Effectiveness and Safety of High-Intensity Interval Training in Patients With Type 2 Deabetes. Diabetes Journal (2015): Volume 28(1): 39-44. ↩︎
  12. Carl DL, et al. Preliminary safety analysis of high-intensity interval training (HIIT) in persons with chronic stroke. Applied Physiology, Nutrition, and Metabolism (2016); 42(3):311-318. ↩︎
  13. Tabata, Izumi, et al. Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max. Medicine and Science in Sports & Exercise. 28 (10): 1327-30. ↩︎
  14. Little JP, et al. (2010). A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: Potential mechanisms. The Journal Of Physiology. 588(6): 1011-22. ↩︎
  15. Zuniga JM, et al. Physiological responses during interval training with different intensities and duration of exercise. Journal of Strength and Conditioning research (2011). 25(5): 1279-84. ↩︎
  16. Hood, MS, et al. (2011). Low-volume interval training improves muscle oxidative capacity in sedentary adults. Medicine & Science in Sports & Exercise. 43(10): 1849-56. ↩︎
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  • Chris

    I typically dislike the HIIT vs regular exercise articles, although I think you did a good job. Exercise is not black/white, on/off or HIIT/continuous. It is a continuum. Therefore, if you exercise at a more strenuous level, you will get more benefit than working out at a less strenuous level. However, as pointed out, in some situations, longer and easier is better. The best approach would almost always be a mix of both, so a few days a week of longer duration lower intensity continuous exercise, and a few days a week of high intensity interval type workouts. There is no new magic here – athletes have been doing interval training for decades. As you correctly pointed out, high intensity exercise is by definition very hard, and many people would not be able to work out that hard on a regular basis. I think your method of exercise is also important. For example the physical stress of running hard vs. cycling hard vs swimming hard. I would guess the more impact in your sport of choice, the higher the chance of injury if you are not careful in working up to high intensity….wonder if there is any good research about that.

    • Michael Curtis

      Absolutely agree with you Chris. Plus we get into specificity training when we train in the sport we are going to be playing. That said, if we are in a high-impact sport, it may not be a bad idea to supplement Training with a low impact alternative. This might reduce risk of injury. If you do find some research on that, please let me know!